South Carolina is among 16 states in the U.S. with the highest risk for earthquakes, according to an update from the U.S. Geological Survey.

The USGS updated its national seismic hazard maps for the first time since 2008 on Thursday. The new study took into account research from the 2011 earthquake and tsunami off the cost of Japan and an earthquake in 2011 in Virginia.

The South Carolina Emergency Management Division says the state generally experiences 15 to 20 earthquakes a year, though many are weak enough to be imperceptible.

In February, there was a 4.1 magnitude earthquake that was felt across the Upstate. It was centered 7 miles west of Edgefield, S.C. It was felt as far west as Atlanta and as far north as Hickory, N.C., each about 150 miles away.

The most infamous and damaging of all South Carolina earthquakes happened in Charleston on the night of Aug. 31, 1886. The earthquake killed about 60 people and destroyed or damaged dozens of buildings. The quake was the strongest earthquake to hit the East Coast. It was felt over a 2.5 million square mile area, from Cuba to New York and Bermuda to the Mississippi River.

Twenty-seven years after the 1886 Charleston earthquake, a 5.5 magnitude earthquake shook Union County on Jan. 1, 1913. There was minimal damage and no deaths, but shock waves were felt as far away as Georgia and parts of Virginia.

According to the Department of Natural Resources, “The majority of earthquakes worldwide occur at plate boundaries when plates stick and then jump past each other. These quakes often are the ones that are the most destructive and well understood in terms of plate tectonics. The cause of earthquakes in South Carolina is not so clear. South Carolina's quakes are located within a plate rather than at a plate boundary. Perhaps the intraplate quakes felt in South Carolina are the result of stresses transmitted inward from the boundaries of the North American plate. In our state, quakes may occur along ancient plate boundaries where existing faults are reactivated as the tectonic stress is released.

“In South Carolina, approximately 70 percent of the earthquakes occur in the Coastal Plain and most are clustered around three areas west and north of Charleston: Ravenel-Adams Run-Hollywood, Middleton Place-Summerville, and Bowman. These faults and other geologic structures related to the earthquakes are hidden by the thick sequence of sediments. Therefore, few clues to the causes of earthquakes in the Coastal Plain can be found at the surface.”